Question: Who was the head of government in North Sumatra Province that ended in 2015-0-0?
Paraphrase: which the head of government  north sumatra province ended in 2015-0-0?
SPARQL (Wikidata): SELECT ?obj WHERE { wd:Q2140 p:P6 ?s . ?s ps:P6 ?obj . ?s pq:P582 ?x filter(contains(YEAR(?x),'2015')) }